喀斯特植被恢复过程中的土壤分形特征

基于粒径的重量分布表征分形维数的计算方法,对喀斯特山区植被恢复过程中的土壤颗粒、团聚体、微团聚体粒径分布的分形维数进行研究,并分析其与土壤理化性质的关系。结果表明,随着植被的不断恢复,>0.25mm水稳性团聚体不断增多,土壤结构不断改善;土壤颗粒分形维数除与土壤水解氮呈显著正相关外(P<0.05),与其他因子的相关性较小,均未达显著性水平;土壤微团聚体和水稳性团聚体分形维数与有机质和全氮、水解氮呈显著负相关,与结构体破坏率呈显著正相关。土壤微团聚体及水稳性团聚体分形维数能较好地反映植被恢复过程中土壤理化性质的演变,可以作为定量评价喀斯特植被恢复过程中土壤结构演变的指标;坡耕地的土壤结构最差,退耕还林有利于喀斯特山区水土保持。

Fractal Features of Soil During the Process of Vegetation Recovery in Karst Region

Calculating the fractal dimensions based on the weight of particle size distribution,fractal dimension of soil particle,soil water-stable aggregates and micro-aggregates during the vegetation restoration process in Karst region were studied and the relationship between soil physical and chemical properties and fractal dimension was analyzed.The results showed that the content of soil water-stable aggregates(>0.25 mm) increased and soil structure improved during the vegetation restoration;the fractal dimension of particle size distribution were dramatically positive correlated with available N(P<0.05),and little correlated with other factors;the fractal dimension of soil micro-aggregates and soil water-stable aggregates were negatively correlated with organic matter,total N and available N,dramatically positive correlated with soil structural destruction ratio.The results indicated the fractal dimension of soil micro-aggregates and soil water-stable aggregates could reflect the characteristics of soil physical and chemical properties and be used as a quantitative index for the assessment of soil structure during the vegetation recovery.Slope farmland had worst soil structure,and returning farmland to forest could be beneficial to soil and conservation in Karst region.